Add cirrusdump action for helpful debugging

Going to /wiki/Page_Name?action=cirrusdump spits out what we have in the
Elasticsearch index for the page.  Two reasons this is cool:
1.  Saves a few steps when we're debugging.
2.  Publicly exposes a safe part of the infrastructure.  Its cool to for
people to look at and allows external users to review what we have either
to suggest things or find bugs or just learn from it.

Bug: 69442
Change-Id: Ic613c2d1a77198a3d2aa7035fd93257f886a2c10
Merge "Add cirrusdump action for helpful debugging"